CELLULAR AND MEDIATOR RESPONSES 24 HOURS AFTER LOCAL ENDOBRONCHIAL ALLERGEN CHALLENGE OF ASTHMATIC AIRWAYS

The effects of acute allergen exposure on bronchoalveolar lavage cells and mediators and mucosal inflammatory cells were evaluated in 10 sub jects with atopic asthma who underwent lavage and biopsy 24 hours segm ental endobronchial allergen challenge. Increased numbers of bronchoal veolar lavage eosinophils were retrieved from the allergen-challenged sites compared with the saline-challenged sites (mean 21.4 vs 1.5 x 10 (3) cells/ml; p < 0.02). Numbers of neutrophils and proportions of CD4 (+), CD8(+), CD25(+), and HLA-DR(+) T cells were similar at the saline - and allergen-challenged sites. In contrast to the bronchoalveolar la vage findings, eosinophil numbers were not increased in the bronchial submucosa or epithelium. There was also no significant difference in n eutrophils, mast cells, CD3(+), CD4(+), or CD8(+) T cells in the submu cosa after allergen challenge, but the number of activated (CD25(+)) T lymphocytes in the mucosa did increase after allergen challenge. Alle rgen challenge did not significant change in endothelial expression of P-selectin, E-selectin, intercellular adhesion molecule-1, or vascula r cell adhesion molecule-1. CD11a(+) and very late antigen-4(+) cell n umbers were similar in the saline- and allergen-challenged sites. This study suggests that in patients with very mild asthma, local allergen challenge induces persistent bronchoalveolar lavage eosinophilia, but the recruitment process seems to have diminished or ceased by 24 hour s.